I did a little reading, and it all comes down to something called "zero stretching" which is essentially breaking the conventional constant-voltage DC power into a stepwise series of square-wave power pulses.
In DCC, power sent to the rail is a generally-symmetric square wave, i.e., short positive pulses followed by short equal-and-opposite negative pulses. The TIME of these pulses is used to send control signals to the trains, much like the funny bar-code things that we see at the store when we buy anything.
However, with "zero stretching", an intentional "break the rules" trick is played ... the duration of a positive pulse is stretched so that it is longer than it's negative-pulse mate. They don't cancel each other, but rather add a net sum greater than zero (in the positive voltage direction). That makes a conventional DC loco go. To go faster, the DCC system extends the biased offset between the positive and negative pulses to yield an even-longer net sum greater than zero.
But all the while, the traditional DC loco is STILL seeing (and receiving) a rapid series of positive and negative pulses ... hence, the "humming noise". And hence, the rationale that this is ultimately bad for the motor to leave the loco sitting idle on the track for any duration.
TJ's disclaimer ... please don't think that I really know what I'm talking about! I'm just babbling after a read of the info below, at this link ...
Hope this helps!
So since I am getting a DCC system will I need a decoder to run more than 1 engine?!Evan,
I've never seen or used one myself, but a Decoder is one of the required brains for a DCC (digital command control) train system, for which one transformer can independently control several trains on one track. The smart systems send out power via a very-rapid set of step-like voltage pulses, sort of like a black-and-white bar code on something you would buy at a store. Each loco needs an onboard Decoder chip that monitors the pulses, looks for a unique signature to see if the "signals and directions" are meant for it, and, if so, operates accordingly (speeds up, stop, etc.)
I had learned a bit about this in another thread, and will quote myself here. Take a look at the link at the end of this ... I found it very useful to understand how DCC works.
Okay Thanks. I have a few more question. How much do each chip cost? And in your oponion what is better, DC or DCC?I hope I'm not wrong in saying this (again, I am NOT a DCC guy), but I believe that you'll need a decoder chip inside EACH loco that you plan to run.
looking for information is just way to much work. why bother googling and looking for it yourself if you can make 0 effort and just post uninformed questions on a forum?All the manufacturers have excellent sites on information on their systems. All you really need to do is read up.
WOW! Thanks alot Bman! This helped me the most!I have the Digitrax Zephyr controller and I think it works great. It's easy to set up and once you get the hang of programming it's not that bad to operate either. The harder part can be installing the mobile decoders in the locos. The Zephyr only allows you to operate 1 DC loco at a time, besides having the decoders in the locos is what DCC is all about. With the decoders you can control lighting, speed match different locos and start, stop and control the speed of each one independently.
I enjoy DCC much much more than the old DC (analog) system
Lol. No I did read it but, since I'm new a modeling I didn't really get it.i guess after all you decided to not read the very long wiki article tworail posted .
Thanks tankist. But I'm done with this. I learned lots of stuff and I decided I will get the Digitrax Zephyr and play around with it. I learned lots of stuff with decoders. Engines already equipped with DCC don't need decoders. At least that what I think. Please tell me if im Wrong.modeling experience has nothing to do with it. i find that the intro paragraph summarises the consept quite well.
i think i already posted the link to http://www.dccwiki.com/Main_Page
this resource has both beginners and advanced information.
PS: for the sake of your engines lives forget about running engines no equipped with decoder on DCC layout. this functionality is only good on paper. in reality engines will heat up (what happens when you put AC power to DC motor?)
you will need a decoder for each engine.
Engines already equipped with DCC already HAVE decoders in them.Engines already equipped with DCC don't need decoders.
Lol, that's what I meant. You don't need them because there already in there.Engines already equipped with DCC already HAVE decoders in them.
saying "Engines already equipped with DCC don't need decoders."Lol, that's what I meant. You don't need them because there already in there.